Process and apparatus for producing laminated safety glass



June 12, 1945. w J. HUBBARD 2,378,016

PROCESS ANDl APPARATUS FOR PRODUCINGLAMINATED SAFETY GLASS Filed Dec. 13, i945 2 sheets-sheet 1 Snvenfor Gttomeg June 12, 1945.4 w. J. HUBBARD 2,378,016

PROCESS AND APPARATUS FOR PRODUQING LAMINATED SAFETY GLASS Filed Dec. 13, 1943 nventor Y W/LL/Aw/ `el HUUB/W0.

Patented Juniz, 194s 'PROESS AND APPARATUS FOR PRQDUC-v ING LAMINATED SAFETY GLASS- William j. 'Humm-a, Toledo, ohio, assigner to Libbey-Qwens-Ford Glass Company, Toledo, Ohio, a corporatlon of' Ohio Application' December 13, 1943-Serial1No. 514,014 v19 Claims. (Cl. 154-4230) The present invention relates to an improved process of and apparatus for producing lami-l nated safety glass.

Laminated safety glass comprises two or more sheets of glass having one or more layers of a -suitable plastic strengthening material interposed therebetween and bonded thereto to provide a composite structure. 'According to one process of producing this type of glass, the glass sheets and plastic interlayerare first properly assembled to provide a so-called sandwich, which is subjected first to a. relatively light initial or preliminary pressing and then to a final heat and pr'essure treatment to complete the compositing of y the laminations. This final heat and pressure treatment is ordinarily carried out in an autoclave, with the sandwich being subjected to the direct action of a fluid under pressure. However,

an improved process and apparatus for prepressing bent or curved laminated safety glass sandwiches whereby the several laminations will be -secured to one another in such a manner that the sandwiches can be subsequently subjected to the direct action of a pressing fluid without danger of the fluid creeping in between the laminabefore being placed in the autoclave, the sandwic isprepressed to remove all trapped air, non-condensable gases, etc., from between the laminations and'to. cause said laminations to stick together to facilitate the subsequent handling thereof as Well as tovprevent the pressing fluid from creeping in between the laminations during the autoclave treatment and causing defects in the finished sheet.

tions.

Another object of the invention is the provision of an improved process and apparatus wherein not only the prepressing of the laminated safety glass sandwiches but also the final heat and fluid pressure treatment thereof can -be accomplished, if desired, in a single`continuous operation.

A further object of the invention is the provision of an improved process and apparatus wherein only the prepressing of the laminated safety glass sandwiches or both the prepressing and final heat and fluid pressure treatment thereof is effected by the application of pressure created by centrifugal force. L

Other objects and advantages' of the invention will become more apparent during the course of the following description when taken in connec- The prepressing of flat sheets of laminated safety glass can be readily accomplished by passing them between one or more pairs of rotatable rolls of a suitable resilient, compresslble material such as rubber. However, this method is not satisfactory in prepressing bent or curved sheets oflaminated safety glass because of the increased handling of the glass, increased time'required for the prepressing operation, and increased liability of breakage. In fact, it is extremely diliicult to prepress curved or bent sandwiches so that they can be submerged unprotected in the autoclave without danger of the pressing uid working in between the laminations, and thisls particularly true in the ase of sheets having irregular or compound curvatures. For this reason, it has been customary to protect the sandwiches from 'the pressing fluid in th'e autoclave by placing them in rubber bags or the like from which the air is exhausted.

It is an aim of this invention to provide an improved' process and apparatus whereby the initial or preliminary pressing of laminated safety `glass sandwiches can be effected in a rapid, em..

tion with the accompanying drawings.

In the drawings wherein like numerals are employed todesignate like parts throughout the' same:

Fig. 1 is a front elevation of one form of apparatus which can be used in carrying out 'the present invention;

Fig. 2 is a vertical section therethrough taken substantially on line 2-2 of Fig. 1, showing a laminated safety glass sandwich in position to be pressed;

Fig. 3 is a horizontal section taken substantially on line 3-3 of Fig. 2; l

Fig. 4- is a verticalsection illustrating the final pressingy of the laminations using a pressing fluid;

position for pressing; and

Fig. 6 ls a similar view showing anotherftype of laminated safety glass.v

With reference now to the drawings, the apparatus herein provided for carrying outthe invention comprises a circular stationary casing Il), having a vertical sidewall II provided at its-upy per edge with an inwardly directed horizontal cient manner and which are especially adaptable to the prepressing of bent or curved sheets of laminated safety glass, although not limited thereto. Another object of the invention is to .provide flange I2 terminating in a down-turned lip I3 to define an opening I4 in the top of said casing.

Arranged Within the casing I0 is a circular container or tub I5 having a bottom I6 and vertical Fig. 5 is an enlarged sectional view of a sheet of regular laminated safety glass supported in side wall I1, said side wall being formed at its upper edge with an inwardly directed flange I8 defining a central opening I9 through which the laminated safety glass sandwiches are introduced into the tub and removed threrefrom afterprocessing. The flange I8 is provided with an offset horizontal supporting ledge 2|) upon which rests a removable cover plate 2|. The container l5 is carried al; the lower end of a vertical shaft 22 driven from a motor 23 supportedmpon a suitable framework made up of a horizontal supporting beam 24 and vertical posts 25 and 26 mounted upon base blocks 21 and 28 respectively, which also support the outer casing- I0.

Arranged within the container I along the side wall I1 thereof and resting freely upon the bottom I6 are one or more removable work supporting units 29. Each of these units includes a base or body member 30 which may be of wood and having its outer surface 3l curved tocorrespond to the curvature of the side wall I1 of the container I5. The inner surface 32 of base member 30 is preferably flat and secured thereto by a suitable type adhesive is a nest block`33 of plaster, plastic or.other preferred material. The inner surface 34 of nest block 33 is shaped to conform to that of the safety glass sandwich which is designated by the letter A. Thus, if flat sheets are to be bonded together, the inner surface of the nest block will be flat, whereas if curved sand-` wiches are to be processed, the inner surface of the nest block will be correspondingly curved as illustrated in the drawings.

After the trapped air has been removed, heat is applied to the laminations without interrupting the speed of rotation of the container to -cause a softening of the plastic interlayer and effect the prepressing of the laminations. This heating can be accomplished in any suitable manner such as by the use of electric resistance units 39 encircling the container I5 and supported in front of reflectors 46 carried by brackets 4I secured to the stationary casing I0. The' temperature of the glass-plastic assemblies A is preferably brought up to around 180 degrees Fahrenheit, where it is vmaintained for approximately ten minutes to complete the prepressing of the laminations.

After being prepressed, the laminated sheets may be removed from the container I 5, and introduced into a separate autoclave where they can be subjected to final heat and pressure treatment to complete the compositing of the laminations. In such an operation, the sheets of safety glass could be subjected to the direct action of a heated fluid at 275 degrees Fahrenheit under 225 pounds pressure per square inch for seven minutes. However, according to the present invention, the nal pressing operation can also be performed in the apparatus herein provided, if desired,y without In Figf is shown a regular laminated safety glass sandwich A composed of two sheets of glass 35 and 36 and an interposed layer of plastic 31. After the glass and plastic laminations have been properly assembled withone another, they are mounted upon the nest block 33 and secured thereto by strips of Scotch tape' 38 or by suitable clamps or the like.

Instead of providing a separate base member 30 and nest block 33, the work supporting unit 29 may be formed of one piece from neoprene, synthetic rubber, or other suitable material.

In carrying out the invention, the desired num-l ber of glass-plastic assemblies A are rst mounted upon the nest blocks 33 after which the work supporting units are arranged on edge around the inside of the container I5 as shown in Figs. 2 and 3, with the glass-plastic assemblies in a vertical position. At this time, the container is at room temperature. After the work, supporting units have been properly arranged, the container is placed in rotation and the'glass-plastic assemblies revolved at a sufficiently high speed and for a sufficient length of time necessary to force all trapped air, non-condensable gases, etc., from between the laminations. Upon being rotated, the inner glass sheet 36 will be forced outwardly by centrifugal force and will thus provide the pressure necessary to expel any trapped air from between the laminations as well as bringing the laminations into intimate contact with one another. The speed of rotation of the container as well as the time cycle will of course vary with different thicknesses of glass sheets and number of laminations. However, by way of example, it has been found that safety glass sandwiches, made up of two sheets of three-sixteenths inch glass and a polyvinyl acetal plastic innerlayer of fteenthousandths inch thickness, can be rotated at 900 R. P. M. for three minutes and that all trapped air will be effectively removed from between the laminations.

interrupting the rotation of the'container I5 or disturbing the position of the prepressed sheets yof safety glass therein.

To secure final pressing of the laminations, a suitable ltype liquid such as hydrocarbon oil, heated to about 300 degrees Fahrenheit, is introduced into the container I5 through the opening I9, and by the rotation of said container is thrown outwardly toward and held against the'sheets of safety glass A by centrifugal force as indicated at 42 in Fig. 4. This will effect an increase in both the temperature of the safety glass and the pressure exerted thereon. After the container has been rotated for from five to six minutes, the oil is permitted to cool down to around 150 degrees Fahrenheit, at which time the container is stopped and the completed units removed. The oil can be drained from the container, when desired, through an outlet 43.

In the type of safety glass shown in Fig. 5, the two sheets of glass 35 and 36 and plastic interlayer 31 are of the same size, with the glass sheets being of the same thickness. However, it will' be readily appreciated that the process and apparatus of this invention can be employed in the prepressing and also for the final pressing, if

' desired, of various types oflaminated safety glass as well as safety glass made up of any preferred number of glass sheets and plastic interlayers and with the glass sheets being of the same or different thicknesses. For example, in Fig. 6 is shown a safety glass unit B including two sheets of glass 44 and 45 and plastic interlayer 46, and in Iwhich the plastic interlayer extends beyond the edges of the glass sheets to provide a iiexible attaching flange 41 in which may be embedded a metal reinforcing member 48. This type of unit has been found extremely satisfactory for use in aircraft windshields and windows, as the extended fiange 41 provides a flexible mounting for the glass which greatly reduces the liability of breakage upon twisting or weaving of the plane. It is also sometimes desirable to build up the thickness of the extended plastic fiange '41 by securing thereto an auxiliary strip of plastic 49. In such case, a strip of rubber or other suitable material 50 is placed inwardly of the plastic ange 41 and held thereaganst by the fastening means 5I which secures the safety glass assembly to the work supporting unit 29. During i the pressing of the laminations, the strip 50 will exert the necessary pressure upon the plastic flange 41 to secure adhesion between said flange and the auxiliary plastic strip 48.

It is to be understood that the form of the invention herewith shown and described is to be taken as the preferred embodiment of the same, and that various changes inthe shape,

size and arrangement of parts maybe resorted to without departing from the spirit of the invention orthe scope of the subjoined claims.

I claim:

1. The process of producing laminated safety glass, vwhich comprises assembling a plurality of glass and plastic laminations to form a sandwich, arranging the. sandwich inA a substantially vertical position, and rotating the sandwich bodi- 1y about a vertical axis to veffect the securing of the laminations together by centrifugal force.

2'. The process of producing laminated safety glass, which comprisesasembling a plurality of glass and plastic laminations to form a sandwich, arranging the sandwich in a substantially vertical position, rotating the sandwich bodily about a vertical axis to effect the securing of the -lamina-*- tions together by centrifugal force, and' heatingv the sandwich during the rotation thereof.

3. The process of producing laminated safetyl glass, which comprises Aasembling a plurality of glass and plastic laminations to form a sandf wich, arranging the sandwich in a substantially vertical position, rotating saidsandwich through a circular path about a vertical axis to effect an initial securingof the laminations together by centrifugal force, and then subjecting the sand-5 wich to fluid pressure while continuing the rota tion thereof to increase the pressure thereon and effect i'lnal bonding of said laminationstogether. 4. The process of producing laminated safety glass, which comprises assembling a pluralityl of glass and plastic laminations tov form a sandwich, arranging the sandwich in asubstantially vertical position, rotating said sandwich through a circular path about a vertical axis to effect an initial securing of the laminations together by centrifugal force, heating the sandwich during the rotation thereof, and then subjecting the sandwich to the action of a heated fluid while continuing the rotation thereof to increase-the temperature thereof and pressure thereon to effect final bonding of said laminations. together.

5. The process of producinglaminated safety glass, which comprises assembling a plurality of glass and plastic laminations to form a sandwich, and rotating the sandwich bodily through a circular path to effect the bonding" of the laminations together by pressure created by the centrifugal force incident to said rotation.

6. The process of producing laminated safety glass, which comprises assembling a plurality of glass and plastic laminations to form a sandwich,

rotating the sandwich bodily through a circular path to effect the bonding of' the laminations together by pressure created by the centrifugal force incident to said rotation, and simultan, eously heating the sandwich during therotation thereof.

'7. The process of producing laminated safety glass, which comprises assembling a plurality of glass and plastic laminations to form a sandwich, subjecting the sandwich to centrifugal force to press the laminations against one another, and simultaneously heating the laminations tol-cause them to adhere to one another.

glass and plastic laminations to form asandwich,

tions together by presure created by the centrifugalforce incident to said rotation, and then sub- -jecting the sandwich to the direct action of fluid undericentrifugal pressure during continued ro` 1o tation of saidfsandwich' to complete 'the bonding of the laminations. i y

' 9. The process "of producing Vlaminated safety glss, which comprises assembling a plurality of glass andplastic laminations to form a sand- 15, wich, rotating the sandwich bodily -through a cir cular path to effect an initial securing vof thev laminations together by pressure created by the,

centrifugal force incident to said rotation, simultaneously heating the sandwich,I and then sub-` 0 jectingvthe sandwich to 'the direct action of avv heated uid under centrifugal pressure during continued rotation of said sandwich -to complete the bonding of the laminations.

l 10. In theproduction of laminated safety glass wherein .glass and plastic laminations' are arranged in properly assembled relationship to form a sandwichv andy subjected rst to a preliminaryv` pressing and then to a final pressure treatment, the stepv of prepressingthe sandv wiches by subjecting them to centrifugal force.

11. In the production of laminated safety glass wherein glass. and plasticlaniinati'ons are arj ranged in properlyv assembled relationship to form a lsandwich and subjected first to apreliminary pressing and then to aflnal pressure f treatment, the `step of prepressing the sandwichesby subjecting them to centrifugal force,

- and simultaneously heating the same.

12. Apparatus .for producing laminated glass' 0 -comprising two sheets of glass and an interposed sheet of plastic material assembled 5to form a sandwich, including a rotatable container for l receiving they sandwich therein, vand meansffor rotating said container to effect the securing of the laminationstogether by pressure 'created by the centrifugal force incident to saidrotatiom 13. Apparatus forproducing laminated glass comprising twosheets ofglass and an interposed sheet of plastic material assembled to form, a

- fsandwich, including a rotatable container for receiving the sandwich'therein, means for rotating said container to effect the securing ofthe lamitainer toeffect the securing vof the laminations 5' 6151. together by pressure created by the centrifugal force incident `to, said rotation.

15. Apparatus for producing laminated'glass Vcomprising two sheets of glassand an interposed sheet` ofvplasticmaterial assembled to `form a means for'securing 4the sandwich to said work supporting unit, means for rotating saidcontainer to"eil.'ect the securing vof the laminations together by pressure created by the'centrifugal `8. of producing laminated safetyv ,-g1ass, which comprises assembling a plurality of rotatingthel sandwich bodily vthrough'a. circular` i 5' path-to effect .an initial lsecuring of the laminato sandwichincluding a rotatable container, a work supporting vunit arranged Within said container,4

force incident to said rotation, and means for heating said sandwich during the rotation thereof.

16. Apparatus for producing laminated glass comprising two sheets of glass and an interposed sheet of plastic material assembled to form a sandwich, including a circular rotatable contain# er, a worksupporting unit arranged within said container and having an inner surface shaped to correspond to the shape of the sandwich, means for securing the sandwich in a substantially ver- .tical position against said work supporting unit,

and means for rotating said container to eeqt vthe securing of the laminations together by vpressure created by the centrifugal force incident to said rotation.

17. Apparatus for producing laminated glass comprising two sheets of glass and an interposed sheet of plastic material assembled to vform a sandwich, including a circular rotatable container. a work supporting unit arranged within said container and having an inner surface shaped to correspond to the shape of the sandwich, means for securing the sandwich in a substantially vertical position against said work supporting unit.

means for rotating said container to effect theV securing of the laminations together by pressure created by the centrifugal force incident to said rotation, and means for heating said sandwich during the rotation thereof,

18. Apparatus for producing bent laminated glass comprising two sheets of glass and an interposed sheet of plastic material assembled to form a sandwich, including a circular rotatable container, a work supporting unit arranged Within said container along the side thereof and hav ing an inner surface curved to correspond to the curvature of the laminations to be joined, means van inner surface curved to correspond to the curvature of the laminations to be Joined, means for securing the assembled laminations in a vertical position to said work supporting unit. means for rotating said container to effect the securing of the laminations together by pressure created by4 the centrifugal force incident to said rotation, and means for heating said sandwich during the rotation thereof.

WILLIAM J. HUBBARD. 

